In recent years, semiconductor integrated circuits have been made highly integrated and large-scale. Furthermore, the semiconductor integrated circuit now comprises a large number of memories. FIG. 18 shows the constitution of a conventional semiconductor integrated circuit. This conventional semiconductor integrated circuit (LSI) 200 comprises many memories 201 such as RAMs and a test logic and design block 202. The test logic is a circuit which executes a test to detect defective memories among the RAMs 201. The design block is a circuit which uses the RAMs 201 to achieve the functions of the LSI 200.
However, if a memory mounted on the conventional LSI becomes defective, it can not be repaired. That is, if even one memory becomes defective, the entire semiconductor integrated circuit is discarded. Consequently, the yield is poor. In particular, the greater the number of memories mounted in the semiconductor integrated circuit, the greater the probability that one of the memories of the semiconductor integrated circuit will be defective, making the yield even worse.